When it comes to rotary-wing aircraft, especially to helicopters, the rotating wings, that is to say, the rotors, have to be braked after the landing on the ground. The rotating wings have to be braked and secured when the aircraft is parked so that they cannot turn, for example, if it is windy. Rotor brakes are needed to achieve this non-rotating state.
German patent specification DE 698 10 025 T2 discloses a rotor brake for a helicopter for purposes of quickly bringing the rotor to a standstill after the landing. This is done mechanically, for instance, with brake calipers.
German patent specification DE 692 08 207 T2 describes a braking unit for use in a rotary-wing aircraft. This unit is designed to stop the rotor as soon as the aircraft has touched the ground. In this context, the phase from the slowdown to the standstill of the rotor should be as short as possible. This is intended to reduce the risk that a blast of wind might cause the rotor disk to tilt so that the rotor could strike passengers just as they are leaving the aircraft, before the rotor has come to a complete standstill. The proposed braking device comprises a hydraulic control motor with a braking force amplifier. The hydraulic control motor encompasses a motor piston that is directly connected to a mechanical transmission means, a free piston that acts upon a friction lining and that has a larger cross section than the motor piston, as well as a control chamber that is formed in a support member between the motor piston and the free piston.
German patent application DE 103 43 055 A1 discloses a rotor brake comprising a brake disk non-rotatingly joined to the rotor shaft, a stationary brake actuator for actuating the brake disk that can be functionally coupled to the brake disk in order to exert a braking effect, and at least one rotor-brake deactivation device that is controlled by the rotor speed and actuated by centrifugal force. The brake actuator is connected to a hydraulic line that supplies the pressure. A piezoelectric actuator can be used instead of the brake actuator.
German patent application DE 101 27 444 A1 discloses a piezoelectric mechanism for generating braking forces, having a number of piezoelectric stepping-drive elements. This mechanism is supposed to refine the principle of a piezoelectric drive so as to yield a practical construction optimized for use as a brake drive or servo drive. In this context, the stepping-drive elements act on the outer circumference of a driven part configured as a threaded spindle.